test/vsock: add install target

Add install target for vsock to make Yocto easy to install the images.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://patch.msgid.link/20240710122728.45044-1-peng.fan@oss.nxp.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>